Re: [PATCH i-g-t] tests/intel/gem_watchdog: Reduced timeouts for worst case scenario

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 12/02/2024 21:23, John.C.Harrison@Intel.com wrote:
> From: John Harrison <John.C.Harrison@Intel.com>
> 
> The watchdog test reduces the watchdog timer from 20s to 1s and then
> uses a 5s timeout waiting for the watchdog to do its stuff. This works
> fine in general, but if an engine reset is required by a context that
> is actually dead for real then a pre-emption timeout must be factored
> in. For RCS/CCS engines, that timeout is 7.5 seconds by default. Thus,
> the test timeout expires first and the test fails.
> 
> Normally, the system is not so dead when running this test as to
> require an engine reset. A simple pre-emption works fine for the
> spinner contexts that is uses. However, there is a hardware workaround
> coming which prevents context switches when both RCS and CCS are busy.
> 
> So add an explicit override of the pre-emption timeout as well as the
> watchdog timeout. That will allow the test to keep working after the
> new w/a lands.
> 
> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
> ---
>   tests/intel/gem_watchdog.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/tests/intel/gem_watchdog.c b/tests/intel/gem_watchdog.c
> index 1e4c350214c0..c9dd0deb51aa 100644
> --- a/tests/intel/gem_watchdog.c
> +++ b/tests/intel/gem_watchdog.c
> @@ -577,6 +577,16 @@ igt_main
>   
>   		i915 = drm_reopen_driver(i915); /* Apply modparam. */
>   		ctx = intel_ctx_create_all_physical(i915);
> +
> +		for_each_ctx_engine(i915, ctx, e) {
> +			/*
> +			 * Context termination by watchdog may require an engine reset. That only
> +			 * occurs after a pre-emption attempt has expired. For RCS/CCS engines,
> +			 * the pre-emption timeout is longer than this test is wanting to wait.
> +			 * So reduce that timeout in addition to the watchdog timeout itself.
> +			 */
> +			gem_engine_property_printf(i915, e->name, "preempt_timeout_ms", "%d", 640);
> +		}

Restore at test exit for subsequent tests to be in a known environment?

Regards,

Tvrtko

>   	}
>   
>   	igt_subtest_group {